Umicore Ag & Co Kg

Ina Grisstede

Thomas Kreuzer

Stephan Eckhoff

Wilfried Mueller

Franz Dornhaus

Alfons Baiker

Ulrich Goebel

Ruediger Hoyer

Stéphanie Frantz

Marek Maciejewski

Meike Wittrock

Jan-Dierk Grunwaldt

Friedemann Rohr

Maria Cristina Casapu

Aflons Baiker

Susanne Philipp

The invention relates to a catalytically active particulate filter which, in addition to the properties typical of particulate filters, has hydrogen sulphide block function, and to a process for removing nitrogen oxides and particulates from the exhaust gas of internal combustion engines operated predominantly under lean conditions (so-called 'lean-burn engines') using the inventive catalytically active particulate filter. This particulate filter comprises a filter body, a copper compound and an oxidation-catalytic active coating which comprises at least one catalytically active platinum group metal. The copper compound is in a second coating applied to the filter body. The two functional coatings may be applied to the filter body consecutive in the direction of flow, i.e. zoned, or layered one on top of the other.

Particulate filter with hydrogen sulphide block function

Nitrogen oxide storage catalysts are used to remove the nitrogen oxides present in the lean exhaust gas of lean-burn engines. As a result of the stress due to high temperatures in vehicle operation, they are subject to thermal aging processes which affect both the nitrogen oxide storage components and the noble metals present as catalytically active components. The present invention provides a process with which the catalytic activity of a nitrogen oxide storage catalyst which comprises, in addition to platinum as a catalytically active component, basic compounds of strontium and/or barium on a support material comprising cerium oxide, said catalytic activity being lost owing to the thermal aging process, can be at least partly restored. The two-stage process is based on the fact that strontium and/or barium compounds formed during the thermal aging with the support material, which also comprise platinum, are recycled to the catalytically active forms by controlled treatment with specific gas mixtures.

Dual-stage method for the reactivation of thermally aged nitrogen oxide storage catalysts

To adhere to legal exhaust-gas regulations, the exhaust gases of a lean-burn engine must be freed from soot particles and nitrogen oxides. It is proposed that the cylinders of the lean-burn engine be divided into two groups which discharge their exhaust gases into two associated exhaust lines which each comprise a soot filter and which are merged at an opening-in point into a common exhaust line. The common exhaust line comprises the catalytic converter for the removal of the nitrogen oxides. By regenerating the two soot filters at different times, the exhaust-gas temperature in the common exhaust line is limited to a mean temperature between the exhaust-gas temperature of normal operation and that of regeneration operation, and the catalytic converter for the removal of the nitrogen oxides is preserved.

Method for regenerating soot filters in the exhaust gas system of a lean mix engine, and exhaust gas system therefor

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Mannheim, Germany

Ina Grisstede